We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next-to-leading order (NNLO). The resulting new chiral force NNLOopt yields chi^2 of approximately 1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A=3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLOopt to study properties of key nuclei and neutron matter, and we demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.

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Thanks:

We thank M.P. Kartamyshev, B.D. Carlsson, and
H.T. Johansson for discussions and related code development. This work was supported by the Research
Council of Norway under contract ISP-Fysikk/216699;
by the Office of Nuclear Physics, U.S. Department of
Energy (Oak Ridge National Laboratory), under Grants
No. DE-FG02-03ER41270 (University of Idaho),
No. DE-FG02-96ER40963 (University of Tennessee),
No. DE-AC02-06CH11357 (Argonne), and No. DE-SC0008499 (NUCLEI SciDAC collaboration); by the
Swedish Research Council (dnr 2007-4078), and by the
European Research Council (ERC-StG-240603). Computer time was provided by the Innovative and Novel
Computational Impact on Theory and Experiment
(INCITE) program. This research used resources of
the Oak Ridge Leadership Computing Facility located
in the Oak Ridge National Laboratory, which is supported by
the Office of Science of the Department of Energy under
Contract No. DE-AC05-00OR22725, and used computational resources of the National Center for Computational
Sciences, the National Institute for Computational Sciences,
and the Notur project in Norway.